Started this as a mail conversation with Dave.H but thought I would move to the forum for others. We don’t have much fault finding in the fault finding guide for Electron.

symptoms:
After machine has been on a few mins the display will start flickering on and off, the flickering gets get worse the longer on, with it off longer and more frequent. The machine does not crash and you can carry on doing what ever it is you are doing, makes playing games hard though.

In the event of fire and/or smoke, call BeebMaster, I mean, in the event that you don't have any 'electronic' freezer spray, if you have a can of air, aka 'air duster', turn the can upside down and spay this on the chip you suspect. Failing that, put the whole naked board in the air path of a powerful fan.

1024MAK wrote:...if you have a can of air, aka 'air duster', turn the can upside down and spay this on the chip you suspect. Failing that, put the whole naked board in the air path of a powerful fan.

If you have some IPA or another alcohol-based cleaner (or even vodka), put a drop or two on one chip at a time and then blow with an air stream - the consequent evaporation will cause the chip to experience significantly greater cooling than by using air alone. Latent Heat of Evaporation and all that....

(Try blowing on the back of your hand and then licking same and blowing - you will notice a big difference.)

In the event of fire and/or smoke, call BeebMaster, I mean, in the event that you don't have any 'electronic' freezer spray, if you have a can of air, aka 'air duster', turn the can upside down and spay this on the chip you suspect. Failing that, put the whole naked board in the air path of a powerful fan.

And yes, a scope (or old style CRT display) may give more hints.

Mark

I do have air spray (not to be confused with hair spray). And a Rigol 1102E.

If you have some IPA or another alcohol-based cleaner (or even vodka), put a drop or two on one chip at a time and then blow with an air stream - the consequent evaporation will cause the chip to experience significantly greater cooling than by using air alone. Latent Heat of Evaporation and all that....

I do have IPA but all out of Vodka, I have some ginger beer as well.

IPA might be the way to go, people might think I am mad if I start buying Vodka for my Computer.

Set up the 'scope on the composite output (monochrome mode) on a working Elk with some chunky graphics showing on screen. E.g. Coloured vertical bars. So that you can actually see the diffent voltage levels for the differently coloured bars on the 'scope.

If available, set the trigger mode to 'TV line' and play until you get the signal for one TV line on the 'scope.

Set up the 'scope on the composite output (monochrome mode) on a working Elk with some chunky graphics showing on screen. E.g. Coloured vertical bars. So that you can actually see the diffent voltage levels for the differently coloured bars on the 'scope.

If available, set the trigger mode to 'TV line' and play until you get the signal for one TV line on the 'scope.

Then, you can connect up the 'scope to the faulty Elk...

Mark

Good idea. Only problem is the faulty Electron IS my working Electron. Unless I fix the two broken Electron's.

Looks like only 6 or 7 IC (depending on MB) deal with video. So not to bad. Although on an Electron that is quite a high percentage. They are mainly 74ls00 ( got spares of those), 74ls86, 74ls08 and 74(L)S74. Will see what others I have tomorrow. Chances are faulty one will be one I don’t have.

Last edited by Elminster on Sat Jul 14, 2018 12:17 am, edited 1 time in total.

Not managed to google definite answer on using plumbers freeze spray, but at the end of the day they are just coolant and propellant. And plumber spray is usually non flammable (probably due to proximity of blow torch) and several say friendly to plastic and ceramic on them. Only thing I am not sure on is temperature.

Was mucky around with Electron for quite sometime and had no flickering issues, I put this down to the fact I was using simple text screens and the AP5 not plugged in etc. Therefore Electron drawing less current and not getting as hot. Once I had the AP5 pluggged back in it started flickering.

It was also stable when I had the AP5 in but an unpopulated Ap6 in my other plus 1. Left that with asteroids load up.

So I think problem is one of current draw, poor circulation and ventilation ( not helped by the MRB). So it could be that I don’t gave a failing part as such. Obvious options are

- better part that works in higher temps
- better ventilation, I.e. try to get a small fan near the psu in the Electron.
- stick some of those mini heat sinks you get for raspberry pi’s

Everything should be well buffered, in respect of the Data lines etc. Which would only leave the power supply! I've carried out lots of tests, recently and BITD, however, there's still a chance you could have a faulty unit. Could you monitor the +5V line at the PSU connector to the main Electron PCB. If you can get a 'scope on there too, especially when it's playing-up - may turn-up more information.

I had problem with my Elk when it 1st arrived doing similar things, I took the ula chip out and cleaned the connections on the chip and the socket connections and not had a problem since. I suspect it was from being stored for a long time.

I had problem with my Elk when it 1st arrived doing similar things, I took the ula chip out and cleaned the connections on the chip and the socket connections and not had a problem since. I suspect it was from being stored for a long time.

Already swapped ULA was the first thing tried. And this one has been in use for good 6 years and been doing this since all the extras got added a couple of years ago.

Edit: I should add the donor Electron is playing up at the moment in other way so I cannot prove 100% I don’t have two bad ULAs but I don’t think so.

Last edited by Elminster on Sat Jul 21, 2018 9:31 am, edited 1 time in total.

Everything should be well buffered, in respect of the Data lines etc. Which would only leave the power supply! I've carried out lots of tests, recently and BITD, however, there's still a chance you could have a faulty unit. Could you monitor the +5V line at the PSU connector to the main Electron PCB. If you can get a 'scope on there too, especially when it's playing-up - may turn-up more information.

Dave H

Yep I can do. My biggest issue is the case has to all be in place or it doesn’t do it. So possibly the gap for the probes may give enoug air flow. Will give it a go.

Now if Martin get the i2c clock module inside he Electron that has a built in temperature sensor on the board..... but I may get also try poking my temperature sensor wand from the multimeter inside and see if I can measure the ambient temperature it’s starts being an issue.